While the official forum is unavailable, try the unofficial one here.Building monuments requires resources. Each monument has three different types.The best chances on a resource is by doing tasks related to the theme of the monument. For Riches of Terra it's groud/earth, like gardening or looking on the globe (also baking).For Flames of Wisdom it's fire, like baking.For Tempest of Bliss it's air, so spraying the bathroom with the new Febreze toilet or catching ghosts.For Springs of Fortune it's water, so diving, showering, washing hands, pool actions.Note: You can get any resource from ANY action! They are rare and few in between, so you have to be patient.

To unlock resources, the cost is 3 LPs for each single resource, so if
your level requires 10 resources of one type, it'll cost you 30 LPs to
unlock that one. Since there are three types, the total would 90 LPs to
unlock them all. Since the requirements increase, so does the cost.
Already collected resources are deducted from the LP price, so if you
had 2 in the previous example, you'll pay 24 LPs instead of 30 LPs.

Completing all four monuments to level 25 results in unlocking the volcano!The first monument available (from game level 15) is "Riches of Terra".

As shown in the picture you start with level 0, to level up you need one of each resource:- Pickaxe- Gold - GraniteFinishing Level 0 gives you a random bonus of § 100.The next level requires two of each resource and adds § to the bonus. With each level increase, so do the resources requirements. So when on level 9 and to reach level 10 you need 10 resources of each.

As shown in the picture you start with level 0, to level up you need one of each resource:- Onyx- Bamboo- Essence of WindCompleting Level 0 decreases the rate at which your Sim's motives drain by 10%.As with every monument, each next level requires one more resource of each and add a % to the decrease of drain.Level 1: 10%Next levels +1% per levelLevel 5: 16%Next levels +0.5% per levelLevel 15: 25%Next levels +0.5% per level Level 25: 35% (Visibly completes the monument, needed to unlock volcano)Next levels +0.5% per levelLevel 50: 47.5%Next levels +0.5% per levelLevel 70: 57.5%

The effects of the monument (affects idle Sims mostly):

The last monument available (at game level 40) is "Springs of Fortune".

As shown in the picture you start with level 0, to level up you need one of each resource:- Limestone- Chisel- PearlUnlocking Level 0 increases your chances on getting XP and Simoleon bonuses from "The Riches of Terra" and "Flames of Wisdom" by 10%.The next level requires two of each resource and adds a % to the bonus. With each level increase, so do the resources requirements. So level 10 needs 11 resources of each.Level 1: 2%Next levels +2% per levelLevel 5: 16%Next levels +2% per levelLevel 10: 26%Next levels +2% per levelLevel 25: 74% (Visibly completes the monument, needed to unlock volcano)Next levels +2% per levelLevel 50: 124%Next levels +2% per levelLevel 70: 164%

Completing all four monuments to level 25 results in unlocking the volcano!

A big thanks to the kind anonymous Dutch lady who helped me out by supplying some of the details.

I have closed the comments for this post, if you are having trouble, please use the unofficial forum, there are many people there who can and likely will answer your questions: http://simsfp.perturbee.netTechnical support (if your game does not work as expected, like no goals, no building options, crashes and such) use: https://firemonkeys.zendesk.com/